BIOL398-04/S15:Jeffrey Crosson Week 2

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Jeffrey Crosson

New Biological Terms


  • Main point
    • Ammonia concentration, not flux, may determine amount of nitrogen metabolism
  • Significance
    • Cells may have a control system via ammonia for nitrogen metabolism
  • Other experiments
    • Shows that flux could have been main driving force over concentration, but due to poor setup
  • General procedure
    • Yeast grown with fixed glucose concentrations and varying ammonia concentrations from 29 - 61 mM
  • Phenomena
    • Metabolism is regulated by extracellualr and intracellular ammonia concentrations, alpha ketoglutarate, glutamine, or glutamate,
  • Conclusion
    • Ammonia concentration may determine nitrogen metabolism in Sacchoromyces cerevisiae cells if so, which identifies the existence of a nitrogen control system

Figure 1B

When input ammonia concentration is above 44 mM, the CO2 production and O2 consumption remained relatively constant. However, at 29 mM the CO2 production increased and O2 consumption decreased. These data indicate that, except at 29 mM ammonia in the feed, no significant changes in the carbon metabolism occurred when the ammonia concentration in the feed was increased and the culture was switched from ammonia limitation to ammonia excess.